Process Overview

Surface planarization using bit grinding is the manufacturing process of removing surface topologies of a wafer using a cutting tool with a bit to achieve the desired workpiece thickness or surface roughness.
The cutting bit is placed vertically to the surface and eccentric to the center of the workpiece and rotated at a high speed. The height of the bit is set to a predetermined value; doing so will process the workpiece to the desired thickness. With this method, the surface of a workpiece that is a few millimeters thick can be flattened and trimmed from a few micrometers to several tens of micrometers.

Because the cutting tool should be more than 3 times harder than a regular cutting tool, a diamond bit is used in surface planarization.
During cutting, water (or pure water) is used for cooling and washing away the cutting debris.

Machines used for high-precision machining

• Fully automatic surface planer

  
  

• Semi-automatic surface planer

  
  

Fully-automatic surface planer

A cassette of workpieces is loaded on the machine. The machine automatically loads, processes and cleans the workpiece and returns it to the cassette automatically.

Semi-automatic surface planer

Loading and cleaning of the workpiece is performed by a human operator.

Tools used for high-precision machining

Diamond bit

Target materials of bit grinding planarization

・Ductile materials（gold, copper, solder, etc.）
・Resin（photoresists, polyimide）
・Resin-metal compounds
・Tape substrates